Field of the Invention
The present invention relates to a method, program, and apparatus for grouping a plurality of elements.
Description of Related Art
In a steel plant, flat steel plates of various sizes are manufactured to order and shipped out. To manufacture flat steel plates, first, a lengthy large steel plate (a large plate) is manufactured through a rolling process. Next, the large plate is cut into multiple steel plates (small plates) of various sizes ordered. Then, the small plates thus cut are examined and shipped out as products.
In cutting out small plates of various sizes from a large plate, some layout of cutting positions produces a large useless area which cannot be used as products, and therefore lowers yield. Accordingly, in a steel plant, in cutting out small plates of various sizes from a large plate, a computer is used to calculate a layout offering good utilization efficiency, so that yield can be improved. To calculate an efficient layout for cutting a large plate into small plates of various sizes is called a plate design problem.
Japanese Patent Application Publication No. 2009-251683 describes an assignment plan making method for making a plan for assigning multiple orders of shaped steel products different in size and amount to multiple pre- or post-rolled materials of various sizes. More specifically, Japanese Patent Application Publication No. 2009-251683 describes an assignment plan making method comprising: a grouping step for classifying materials into multiple groups according to size; a pattern creating step for obtaining multiple patterns assignable to one piece of material according to the sizes of orders under predetermined patterning conditions; and a pattern selecting step for selecting patterns necessary for the assignment to the material by obtaining allocation of the patterns to the group according to at least an evaluation function indicating a score of material yield.
Japanese Patent Application Publication No. 2001-184112 describes a method for automatically making a cutting plan of parts, the method making a layout of the parts on a plate material based on data on the parts and data on the plate material. More specifically, Japanese Patent Application Publication No. 2001-184112 describes a method for automatically making a cutting plan of parts, which comprises the steps of: determining the yield of each plate material on which parts are laid out; and editing the parts laid out on a plate material having yield equal to or less than a specified amount to locate the parts at a predetermined position on the plate material.
Japanese Patent Application Publication No. 2007-137612 describes a method for planning division of multiple steel materials in a steel-material yard, the method dividing multiple target steel materials waiting to be supplied to the next step in a steel process or waiting to be shipped, into multiple mounds of steel materials based on predetermined mounding constraints. More specifically, Japanese Patent Application Publication No. 2007-137612 describes a method for planning division of steel materials, the method including: generating a set of feasible mounds which are subsets of the target steel materials; setting a constraint (set division constraint) used for obtaining such combinations of feasible mounds from the set of feasible mounds that each combination includes all the target steel materials without duplication; and figuring out a combination of feasible mounds which optimizes an evaluation function based on the group division constraint.